High-speed railway-brake.



No. 720,827. A PATENTED FEB. 17, 1903. W. B. MANN. HIGH SPEED RAILWAY BRAKE.

APPLIGATION FILED MAY 14, 1902.

N0 MODEL. ZSHEETS-SHEET 14 a A l 1 a A R i1 g I? a l l A h A A; $1

Q in u I Q gwoenkoz Witnesses b I It i UNITED STATES PATENT OFFICE.

WILLIAM B. MANN, OF BALTIMORE, MARYLAND.

HIGH-SPEED RAILWAY- BRAKE.

SPECIFICATION forming part of Letters Patent No. 720,827, dated February 17, 1903. Application filed May 14, 1902. Serial No. 107,289. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM B. MANN, a resident of Baltimore, Maryland, have in vented a new and useful Improvement, in High- Speed Railway-Brakes, which invention is fully set forth in the following specification.

My invention relates to air-brakes for railway-trains, and more especially to what are known as high-speed brakes. The growing tendency of railway management at the present time is to run all trains, both passenger and freight, at a higher rate of speed, and this has introduced new difiiculties into the practical operation of air-brakes. In order that these high-speed trains may be quickly and safely handled by the engineer, it is essential that the braking pressure per unit of surface should greatly exceed that heretofore found GffiGlGIlli for trains of lower speed; but if the high braking pressure per unit of surface is maintained after the speed of the train has been reduced it causes the wheels to slide,

thereby flattening them and bringing about their speedy destruction. Edorts have heretofore been made to regulate this braking pressure per unit of surface and reduce the same as the speed of the trainslackens, and for this purpose it has been proposed to lower the braking pressure by permitting air to slowly escape from the brake-cylinder through the medium of the triple valve until the desired minimum pressure is secured in the brake-cylinder. This is objectionable, because the accuracy and reliability of the triple valve depend to a large extent upon its simplicity of construction, and any addition to the functions of the triple valve inevitably tends to complicate it and detract from its reliability of action.

The object of the present invention is to provide a high-speed brake by which a high braking pressure may be applied during the time that the train is traveling at a high speed and which shall automatically decrease the braking pressure until it equals any predetermined amount and which shall do this without in any way changing the functions of the triple valve as now employed or imposing any additional labor thereon.

With this object in view the invention consists of a brake-cylinder of ordinary or usual construction connected with the auxiliary reservoir through a triple valve and having a piston through which is provided an opening leading from the auxiliary-reservoir side of the piston to the atmosphere side thereof and a valve normally closing said opening and provided with means which operate to lift said valve and permit air to escape from the brake-cylinder when the braking pressure upon the wheels has reached a predetermined amount per unit of surface. The escape of the air from the brake-cylinder is gradual, thereby gradually decreasing the brake-cylinder pressure as the speed of the train decreases, and, finally, when the pressure has been decreased to a predetermined point the valve is permitted to close automatically and retain the usual or any predetermined pressure in the brake-cylinder. Moreover, the entire construction of parts is such that all slack in the brake-gear (due to wearing of pivotal connections between the piston-rod of the brake -cylinder and the brake-shoe) is taken up at all times, thereby insuring the uniform application of the brakes on all the cars of the train.

, I have illustrated the invention in the accompanying drawings, in which- Figure 1 shows a longitudinal section of a brake-cylinder and its connected parts with the brakes released. Fig. 2 is a similar view with the brakes applied at high-speed pressure, and Fig. 3 is an enlarged view of a detail.

Referring to the drawings, 1 is the brakecylinder, of any suitable construction, communicating with the auxiliary reservoir 2 by way of the pipe 3. Within the cylinder 1 is a piston l, provided with a suitable packingring 5, of leather or other proper material, clamped to the piston by'means of the clamping-ring 6 and bolts 7 7, while an annular spreader 8 is employed to keep the packing snugly. against the walls of the cylinder. This forms an efficient and economical packing and is one I prefer to employ; but the end and has the usual spring 9 normally holdi ing the piston in the front end of the cylinder, said spring being coiled around a tube 10, which plays freely in and out of the rear open end of the brake-cylinder. In the forward end of this tube 10 is secured a plug 11, provided with a screw-threaded projection 12, the plug 11 being secured to the tube 10 in any suitable way, as by screws 13, Fig. 3. The plug 11 has a tubular rearward extension 14 fitting snugly within the tube 10, and a sliding block 15 fits loosely within said extension 14 and is retained and guided therein by means of a cross-pin 16, Whose ends project from the block and enter slots 17, formed in the walls of the extension 145 of plug 11. The rear face of block 15 is concave and the front face is a plane surface and forms a seat for a strong and finely-tempered spring 18, whose other end bears against the rear face of the plug 11. The rear side of the piston 4 has a boss 19, within which the forward end of the tube 10 snugly fits, the plug 11 engaging a screw-threaded seat in the piston 4. This piston is provided with a restricted central opening 20, which registers with an opening 21 through the plug 11, a valve 22 being seated in said opening 21 and normally resting a slight distance from the front of the block 15. (See Fig. 3.) As before stated, the rear face of this block is concave and the forward end of the piston-rod 24is convex and bears against the concave face of the block 15, while the rear end of the rod 24 is connected to the brakegear at 25 in the usual or any suitable way.

The normal position of the parts is shown in Fig. 1, the brakes being released and the brake-cylinder 1 being in connection with the atmosphere via pipe If new the train be running at a high rate of speed and a high air-pressure of, say, ninety pounds per square inch be maintained in the auxiliary reservoir, the parts will take the position shown in Fig. 2 upon an emergency application of the brakes-that is to say, the brakes will be applied to the rapidly-revolving wheels with apressure approximatingseventy-fivepounds per square inch in the brake-cylinder, which will force the piston rearward and compress the spring 18 between the plug 11 and sliding block 15 until the sliding block strikes the stem 26 of the valve 22 and lifts the valve off its seat, thereby permitting air to slowly escape from the brake-cylinder through the ports 20 and 21 and past the sliding block 15 to the atmosphere, thereby gradually 1owering the pressure within the brake-cylinder until it is less than that of the spring 18, when the piston 4 will move slightly to the left of the position it occupies in Fig. 2 and the valve 22 will close and prevent any further escape of air from the brake-cylinder. The tension of spring 18 may be so adjusted as to cause the closing of valve 22 at any desired pressure in the brake-cylinder. Thus in the above example if there were a pressure of seventy-five pounds per square inch in the brake-cylinder when the brakes are first ap plied the brake-shoes would bear with so great a force upon the wheels as to cause them to slide but for the high speed at which the wheels are revolving, and as this speed gradually slackens under the application of the brakes the braking force decreases by reason of the leak past the valve 22 until said valve closes, after which the pressure in the brake-cylinder remains constant. If, therefore, it be desired to have this last-mentioned constant pressure equal to fifty-five pounds per square inch, the spring 18 would be such as not to yield sufficiently to open the valve under any pressure less than fifty-five pounds. It will be observed that this spring 18 forms, as it were, a yielding connection between the piston at and the piston-rod 24: and holds the latter at all times pressed firmly to the rear, thereby taking up any slack that may be due to, wearing of the pivotal connections between the rods and the levers of the brakegear. This is a matter of considerable importance, as it secures an even and simultaneous impact of the brake-shoes of all the cars of a train and avoids the jars and strains due to the uneven gripping of the brakeshoes.

Having thus described the invention, what I claim is 1. In a railway-brake, a brake-cylinder and piston, and means operated by said piston for reducing the pressure in said cylinder to a predetermined point when the brakes are applied.

2. In a railway-brake, a brake-cylinder, a

piston therein, a valved outlet from said cylinder on the pressure side of said piston, and means actuated by said piston in applying the brakes to open said outlet.

3. In a railway-brake, a brake-cylinder, a piston therein, a passage leading through said piston from the auxiliary-reservoir side thereof to the atmosphere, a valve closing said passage, and means actuated by the piston to open said valve.

4. In a railway-brake, a brake-cylinder, a piston and piston-rod therein, a port in said piston leading from the auxiliary-reservoir side thereof to the atmosphere, a valve normally closing said port, and means actuated by the piston-rod to open said valve when the brakes are applied.

5. In a railway-brake, a brake-cylinder, a piston and piston-rod therein, a port leading from the pressure side of said piston to the atmosphere, a valve controlling said port, and means within the cylinder for opening said valve when the brakes are applied.

6. In a railway-brake, a brake-cylinder, a piston therein, a port leading from the pressure side of said piston to the atmosphere, a valve normally closing said port, devices for opening said valve, and means holding said devices inoperative in the absence of a predetermined pressure in the cylinder.

7. In a railway-brake, a brake-cylinder, a piston therein, a passage leading from the pressure side of said piston to the atmosphere, a valve in said passage,- means for opening said valve, and a tension device within the cylinder holding said means inopment of the piston-rod, and a spring interposed between said rod and piston.

10. In a railway-brake, a brake-cylinder, a piston having a cylindrical boss on its rear side, a slide movable in said boss, a pistonrod bearing on said slide and connected to the brake-gear, a passage leading from the front or pressure side of said piston into the boss, a valve closing said passage in the line of movement of said slide, and a spring interposed between the slide and piston.

In testimony whereof I have signed this specification in the presence of two subscribin g witnesses.

WILLIAM B. MANN.

Witnesses:

Tnos. KENT BRADFORD,

AUG. W. BRADFORD. 

